First working draft of new payload system.

IPython/core/interactiveshell.py

@@ -1901,6 +1901,9 b' class InteractiveShell(Configurable, Magic):'
           - 1: an error occurred.
         """
 
+        # Clear the payload before executing new code.
+        self.payload_manager.clear_payload()
+
         # Set our own excepthook in case the user code tries to call it
         # directly, so that the IPython crash handler doesn't get triggered
         old_excepthook,sys.excepthook = sys.excepthook, self.excepthook

IPython/core/payload.py

@@ -32,10 +32,10 b' class PayloadManager(Configurable):'
     def write_payload(self, data):
         if not isinstance(data, dict):
             raise TypeError('Each payload write must be a dict, got: %r' % data)
-        self.payload.append(data)
-
-    def reset_payload(self):
-        self.payload = []
+        self._payload.append(data)
 
     def read_payload(self):
         return self._payload
+
+    def clear_payload(self):
+        self._payload = []

IPython/frontend/qt/console/rich_ipython_widget.py

@@ -60,20 +60,28 b' class RichIPythonWidget(IPythonWidget):'
         """ Reimplemented to handle matplotlib plot payloads.
         """
         payload = msg['content']['payload']
-        plot_payload = payload.get('plot', None)
-        if plot_payload and plot_payload['format'] == 'svg':
-            svg = plot_payload['data']
-            try:
-                image = svg_to_image(svg)
-            except ValueError:
-                self._append_plain_text('Received invalid plot data.')
-            else:
-                format = self._add_image(image)
-                format.setProperty(self._svg_text_format_property, svg)
-                cursor = self._get_end_cursor()
-                cursor.insertBlock()
-                cursor.insertImage(format)
-                cursor.insertBlock()
+        if payload:
+            for item in payload:
+                if item['type'] == 'plot':
+                    if item['format'] == 'svg':
+                        svg = item['data']
+                        try:
+                            image = svg_to_image(svg)
+                        except ValueError:
+                            self._append_plain_text('Received invalid plot data.')
+                        else:
+                            format = self._add_image(image)
+                            format.setProperty(self._svg_text_format_property, svg)
+                            cursor = self._get_end_cursor()
+                            cursor.insertBlock()
+                            cursor.insertImage(format)
+                            cursor.insertBlock()
+                    else:
+                        # Add other plot formats here!
+                        pass
+                else:
+                    # Add other payload types here!
+                    pass
         else:
             super(RichIPythonWidget, self)._process_execute_ok(msg)
 

IPython/zmq/ipkernel.py

@@ -49,9 +49,6 b' class Kernel(Configurable):'
     pub_socket = Instance('zmq.Socket')
     req_socket = Instance('zmq.Socket')
 
-    # The global kernel instance.
-    _kernel = None
-
     # Maps user-friendly backend names to matplotlib backend identifiers.
     _pylab_map = { 'tk': 'TkAgg',
                    'gtk': 'GTKAgg',
@@ -69,9 +66,6 b' class Kernel(Configurable):'
         self.shell.displayhook.session = self.session
         self.shell.displayhook.pub_socket = self.pub_socket
 
-        # Protected variables.
-        self._exec_payload = {}
-        
         # Build dict of handlers for message types
         msg_types = [ 'execute_request', 'complete_request', 
                       'object_info_request', 'prompt_request',
@@ -80,11 +74,6 b' class Kernel(Configurable):'
         for msg_type in msg_types:
             self.handlers[msg_type] = getattr(self, msg_type)
 
-    def add_exec_payload(self, key, value):
-        """ Adds a key/value pair to the execute payload.
-        """
-        self._exec_payload[key] = value
-
     def activate_pylab(self, backend=None, import_all=True):
         """ Activates pylab in this kernel's namespace.
 
@@ -126,21 +115,9 b' class Kernel(Configurable):'
 
         matplotlib.interactive(True)
 
-    @classmethod
-    def get_kernel(cls):
-        """ Return the global kernel instance or raise a RuntimeError if it does
-        not exist.
-        """
-        if cls._kernel is None:
-            raise RuntimeError("Kernel not started!")
-        else:
-            return cls._kernel
-
     def start(self):
         """ Start the kernel main loop.
         """
-        # Set the global kernel instance.
-        self.__class__._kernel = self
 
         while True:
             ident = self.reply_socket.recv()
@@ -169,9 +146,6 b' class Kernel(Configurable):'
         pyin_msg = self.session.msg(u'pyin',{u'code':code}, parent=parent)
         self.pub_socket.send_json(pyin_msg)
 
-        # Clear the execute payload from the last request.
-        self._exec_payload = {}
-
         try:
             # Replace raw_input. Note that is not sufficient to replace 
             # raw_input in the user namespace.
@@ -182,7 +156,6 b' class Kernel(Configurable):'
             self.shell.displayhook.set_parent(parent)
 
             self.shell.runlines(code)
-            # exec comp_code in self.user_ns, self.user_ns
         except:
             etype, evalue, tb = sys.exc_info()
             tb = traceback.format_exception(etype, evalue, tb)
@@ -196,7 +169,11 b' class Kernel(Configurable):'
             self.pub_socket.send_json(exc_msg)
             reply_content = exc_content
         else:
-            reply_content = { 'status' : 'ok', 'payload' : self._exec_payload }
+            payload = self.shell.payload_manager.read_payload()
+            # Be agressive about clearing the payload because we don't want
+            # it to sit in memory until the next execute_request comes in.
+            self.shell.payload_manager.clear_payload()
+            reply_content = { 'status' : 'ok', 'payload' : payload }
 
         # Compute the prompt information
         prompt_number = self.shell.displayhook.prompt_count

IPython/zmq/pylab/backend_payload.py

@@ -2,7 +2,7 b''
 """
 
 # Local imports.
-from IPython.zmq.ipkernel import Kernel
+from IPython.core.interactiveshell import InteractiveShell
 
 
 def add_plot_payload(format, data, metadata={}):
@@ -19,5 +19,5 b' def add_plot_payload(format, data, metadata={}):'
     metadata : dict, optional [default empty]
         Allows for specification of additional information about the plot data.
     """
-    payload = dict(format=format, data=data, metadata=metadata)
-    Kernel.get_kernel().add_exec_payload('plot', payload)
+    payload = dict(type='plot', format=format, data=data, metadata=metadata)
+    InteractiveShell.instance().payload_manager.write_payload(payload)